Thermographically determined specific absorption rate patterns of 434-MHz applicators

Area of Science:

• Biomedical Engineering
• Medical Physics
• Thermal Therapy

Background:

• Hyperthermia therapy utilizes localized heating to treat various medical conditions.
• Accurate assessment of specific absorption rate (SAR) is crucial for effective and safe hyperthermia treatment.
• Understanding SAR distribution from applicators is essential for optimizing treatment planning.

Purpose of the Study:

• To evaluate and compare the specific absorption rate (SAR) patterns of two 434-MHz hyperthermia applicators (TCA 434-1 and TCA 434-2).
• To determine the influence of applicator contact and spacing on SAR distribution within a phantom model.
• To assess the clinical applicability of the evaluated hyperthermia applicators.

Main Methods:

• Thermographic evaluation of SAR patterns using a multi-layered phantom model (fat and muscle).
• Calculation of SAR based on temperature rise, net input power, exposure time, and tissue-specific heat.
• Investigation of SAR distribution with direct applicator contact and with 0.8-cm polystyrene foam spacing.

Main Results:

• High localized SARs were observed along the broad sides of applicators during direct contact with the phantom.
• Uniform SAR distribution was achieved within the applicator aperture when using a 0.8-cm polystyrene foam spacing.
• Both applicators exhibited similar SAR patterns, but TCA 434-1 demonstrated better clinical suitability due to its smaller size.

Conclusions:

• The TCA 434-1 and TCA 434-2 applicators show comparable SAR patterns, with spacing significantly improving uniformity.
• The TCA 434-1 applicator is recommended for clinical applications owing to its smaller dimensions and effective SAR distribution.
• Thermographic evaluation in phantom models is a valuable method for assessing hyperthermia applicator performance.